1. Field of the Invention
The present invention relates to a discharge lamp unit composed of a supporting member that supports a discharge lamp, and a circuit substrate for mounting circuit elements (or circuit components) from which electric power is supplied to the discharge lamp.
2. Description of the Related Art
There are conventional techniques regarding discharge lamp units. Each of the conventional discharge lamps is composed mainly of a discharge lamp, a supporting member, and a circuit substrate. For example, a conventional discharge lamp unit uses a housing case capable of accommodating the circuit substrate. The housing case is made of a material of a low heat conductivity in order to prevent conduction of heat energy generated in the discharge lamp to the circuit substrate on which circuit elements (or circuit components) are mounted. Japanese patent laid open publication No. JP 2003-022702 discloses such a conventional technique regarding the discharge lamp unit.
In the conventional discharge lamp unit, the supporting member and an outer peripheral wall of the housing case are assembled together, where the supporting member supports the discharge lamp. When the outer peripheral wall of the housing case is heated by heat energy generated in the discharge lamp, it is difficult to prevent the conduction of heat energy to the circuit substrate.